Another Outlook Autocomplete question

Hi,

A few users on my network are experiencing an issue with their outlook autocomplete. They are using Windows XP with Microsoft Outlook 2007. When new contacts are added, they lose their autocomplete functionality. When they send e-mails they regain their ability to use the feature with that contact until new contacts are added again.
Now for a short term fix, I’ve given them the .nk2 tool that allows them to fill it with their contacts, but I’d like to fix it for them without them having to do their extra step. The main concern is the owner is one of the ones having the problem.

Thanks,

Joseph